1. Field of the Invention
The present invention relates to a 3-D crimp polyethylene terephthalate multifilament (Bulked Continuous Filament, hereinafter referred to as “BCF”) has a stress-strain curve that (a) the 3-D crimp polyethylene terephthalate multifilament elongates less than 5.0% when subjected to an initial stress of 1.0 g/d, (b) it has an initial modulus of 20 to 60 g/d, (c) it elongates at least 20% when subjected to a stress region of 1.0 to 2.5 g/d, and (d) it elongates from a tensile strength of at least 3.0 g/d to the tensile strength at break.
2. Description of the Related Art
A synthetic fiber material of a BCF that is used to produce typical carpets is exemplified by polypropylene and polyethylene terephthalate, in addition to nylon as a representative material. Particularly, a process of producing BCF and carpets using a polyethylene terephthalate material has recently come into the spotlight. The reason is that the polyethylene terephthalate material has better characteristics than other materials in view of economic efficiency.
For flame retardancy of fibers, there are generally two methods, one of which is treatment of flame retardation to the fibers. The other method is flame retardation of a polymer using a fiber material, and this method result in lasting effect of flame retardancy. The treatment of the flame retardation to the fibers is largely applied to natural fibers such as cotton in the related art, and currently, also applied to synthetic fibers. However, the treatment of the flame retardation by the post-process result in poor durability of the fiber and environmental pollution due to wastewater generated during the treatment process, thus being tending to decrease.
Meanwhile, the method of flame retardation of the polymer is generally used a method of copolymerization to provide the fiber having the lasting flame retardancy. For copolymerization, various flame retardants having reactivity have been manufactured industrially.
Bromine- and phosphorus-based flame retardants are frequently applied to produce the polyethylene terephthalate having flame retardancy using the copolymerization. Japanese patent laid-open publication Nos. 1987-6912 and 1978-46398 is disclosed the bromine-based flame retardant. Since a bromine-based compound is easily thermally decomposed at high temperatures, the compound is necessary to be added in a great amount in order to obtain effective flame retardancy. Thus, the polymer is discolored and has deteriorated lightfastness. Furthermore, recently, the possibility of generation of a carcinogenic substance such as dioxin and benzofuran has been suggested, thus there is an attempt to restrict the use of the bromine-based compound. Currently, replacement into the phosphorus-based flame retardant is actively conducted.